Fire detection systems are widely used today in many environments, particularly those have a high risk of hydrocarbon fires, such as petrochemical plants and off-shore oil rigs. In these environments, the systems must detect a fire rapidly, discriminate it from false alarms conclusively, trigger an alarm automatically and release suppressant reliably to control it quickly, so that no lives are lost and no properties are damaged. All commercially-available systems using simple determination of fire energy for detection suffer in varying degree from false alarms, poor reliability and slow response, each causes untimely suppressant release proved costly and hazardous to the user. Many industries need a more sophisticated system which eliminates or significantly reduces false alarms by discriminating the flame from false alarms originated from all sources, rapidly and reliably, while at the same time being affordable to the user. This invention is such a system capable of imaging the flame and using its spectral, spatial and temporal characteristics to discriminate it from false alarms.